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Delayed
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Delayed

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Delayed[expr]

represents an expression whose evaluation is delayed until its value is externally requested.

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Delayed[expr,fmt]

specifies that the result from evaluating expr should be given in format fmt.

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Delayed[expr,{fmt,rform}]

specifies that the result should be given as a response of the form rform.

Details and Options

Examples

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Basic Examples  (1)Summary of the most common use cases

Delayed specifies that the expression should not be evaluated until it is requested:

In[1]:=1
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https://wolfram.com/xid/0bn6lgq-eerahn
Out[1]=1

This link gives the current time. Revisiting the link gives the new time:

In[2]:=2
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https://wolfram.com/xid/0bn6lgq-owv46o
Out[2]=2

Options  (2)Common values & functionality for each option

CachePersistence  (1)

Deploy a Delayed that gives the current time and caches its result for up to 3 seconds:

In[1]:=1
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https://wolfram.com/xid/0bn6lgq-ncad6j
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0bn6lgq-obvh7p
Out[2]=2

UpdateInterval  (1)

Deploy a Delayed that refreshes every 3 seconds when displayed in a web browser:

In[1]:=1
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https://wolfram.com/xid/0bn6lgq-4plix4
Out[1]=1

Possible Issues  (1)Common pitfalls and unexpected behavior

Since the default ExportForm of Delayed[expr] is HTMLFragment, an expression evaluating to None will be returned as an empty string:

In[1]:=1
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https://wolfram.com/xid/0bn6lgq-dcqx9j
Out[1]=1

In order to get the correct value in the above example, specify the format of Delayed[expr] as Wolfram Language:

In[2]:=2
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https://wolfram.com/xid/0bn6lgq-yl7hoo
Out[2]=2
Wolfram Research (2014), Delayed, Wolfram Language function, https://reference.wolfram.com/language/ref/Delayed.html (updated 2014).
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Wolfram Research (2014), Delayed, Wolfram Language function, https://reference.wolfram.com/language/ref/Delayed.html (updated 2014).

Text

Wolfram Research (2014), Delayed, Wolfram Language function, https://reference.wolfram.com/language/ref/Delayed.html (updated 2014).

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Wolfram Research (2014), Delayed, Wolfram Language function, https://reference.wolfram.com/language/ref/Delayed.html (updated 2014).

CMS

Wolfram Language. 2014. "Delayed." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014. https://reference.wolfram.com/language/ref/Delayed.html.

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Wolfram Language. 2014. "Delayed." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014. https://reference.wolfram.com/language/ref/Delayed.html.

APA

Wolfram Language. (2014). Delayed. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Delayed.html

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Wolfram Language. (2014). Delayed. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Delayed.html

BibTeX

@misc{reference.wolfram_2025_delayed, author="Wolfram Research", title="{Delayed}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/Delayed.html}", note=[Accessed: 01-May-2025 ]}

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@misc{reference.wolfram_2025_delayed, author="Wolfram Research", title="{Delayed}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/Delayed.html}", note=[Accessed: 01-May-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_delayed, organization={Wolfram Research}, title={Delayed}, year={2014}, url={https://reference.wolfram.com/language/ref/Delayed.html}, note=[Accessed: 01-May-2025 ]}

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@online{reference.wolfram_2025_delayed, organization={Wolfram Research}, title={Delayed}, year={2014}, url={https://reference.wolfram.com/language/ref/Delayed.html}, note=[Accessed: 01-May-2025 ]}